Self-stabilizing suspension and hoisting system

Abstract

A load hoisting system for raising and lowering a load. A first line supports a rigid beam with unequal mechanical advantages on either side of the load. A second line supports the same rigid beam with mechanical advantages on either side of the load that are, in total, equal to those on the first line but with a ratio of mechanical advantages unequal to the ratio of mechanical advantages of the first line. One end of each line is fastened to a fixed support and the other ends of the two lines are drawn at the same rate by a power source, which system eliminates all axial rotation of the beam. The system may be applied to both ends of a long load by drawing of all lines in synchronism, advantageously being applied to lift both ends of a boat.

1. A hoist and suspension system for raising and lowering a load comprising:
 first and second rigid supports, one on each side of the load; 
 a first inextensible line fastened to said first rigid support and passing over and under a plurality n a  of pulleys including a pulley connected at a first end of a rigid beam which supports the load, said first line extending along said beam beneath the load, said first line passing to another plurality n b  of pulleys including a pulley at said second end of said rigid beam and thence to a power source fixed to said second rigid support to which said first line is connected; 
 a second inextensible line spaced adjacent said first line and fastened to said first rigid support and passing over and under the plurality m a  of pulleys including a pulley connected at the first end of said beam, said second line extending along said beam and beneath the load, said second line passing to the plurality m b  of pulleys including a pulley at a second end of said beam and thence to said power source fixed on said second rigid support to which said second line is connected; 
 said first and second lines and corresponding pulleys producing mechanical advantages n a  and m a  on the first side of the load and mechanical advantages n b  and m b  on the other side of the load, respectively; 
 said total mechanical advantage n a  and n b  of said first line being equal to said total mechanical advantage of m a  and m b  said second line expressed as:
     m   a   +m   b   =n   a   +n   b    
 
 said ratio of said mechanical advantages of one line being unequal to said ratio of said mechanical advantages of said other line expressed as:
     m   a   /m   b   ≠n   a   /n   b    
 
 whereby said load is raised and lowered by said power source without said lines or said beam passing over the load, and without rotation of the load about a horizontal axis perpendicular to said rigid beam, with a positive resistance to rotation that increases expressed as:
   |n a m b −n b m a |. 
 
 
   
   
     2. A hoist and suspension system for raising and lowering an elongated load comprising:
 first and second rigid support one on each side of the load; 
 two spaced apart rigid beams each supporting one end of the load; 
 a first inextensible line fastened to said first rigid support and passing over and under a plurality n a  of pulleys including a pulley connected at a first end of each of said beams, each said first line extending along said beam and passing to another plurality n b  of pulleys including a pulley at said second end of said rigid beam and thence to a power source fixed to said second rigid support to which said first line is connected; 
 a second inextensible line spaced adjacent said first line and fastened to said first rigid support and passing over and under the plurality m a  of pulleys including a pulley connected at the first end of each of said beams, each said second line extending along said beam, said second line passing to the plurality n b  of pulleys including a pulley at a second end of said beam and thence to said power source fixed on said second rigid support to which said second line is connected; 
 said first and second lines and corresponding pulleys producing mechanical advantages n a  and m a  on the first side of the load and mechanical advantages n b  and m b  on the other side of the load, respectively; 
 said total mechanical advantage n a  and n b  of each of said first lines being equal to said total mechanical advantage m a  and m b  of each of said second lines expressed as:
     m   a   +m   b   =n   a   +n   b    
 
 said ratio of said mechanical advantages of one line being unequal to said ratio of said mechanical advantages of said other line expressed as:
     m   a   /m   b   ≠n   a   /n   b    
 
 whereby said load is raised and lowered by said power source without said lines or said beam passing over the load, and without rotation of the load about a horizontal axis perpendicular to said rigid beam, with a positive resistance to rotation that increases expressed as:
   |n a m b −n b m a |. 
 
 
   
   
     3. A hoist and suspension system for raising and lowering a load comprising:
 first and second rigid supports, one on each side of the load; 
 a first inextensible line fastened to said first rigid support and passing under a pulley connected at a first end of a rigid beam which supports the load, said first line then extending along said beam beneath the load and passing under another pulley connected at said second end of said rigid beam, over another pulley fastened to said second rigid support, under another pulley connected at said second end of said rigid beam, over another pulley fastened to said second rigid support, and thence to a power source fixed to said second rigid support to which said first line is connected; 
 a second inextensible line spaced adjacent to said first line and fastened to said first rigid support and passing under a pulley connected at the first end of said beam, over another pulley fastened to said first rigid support, under another pulley connected at said first end of said rigid beam, said second line then extending along said beam and passing under another pulley connected at said second end of said rigid beam, over another pulley fastened to said second rigid support and thence to said power source fixed on said second rigid support to which said second line is connected; 
 said first and second lines and corresponding pulleys producing total mechanical advantages which are equal one to another; 
 said load is raised and lowered by said power source without said lines or said beam passing over the load, and without rotation of the load about a horizontal axis perpendicular to said rigid beam.